On the basis of principle of multitasking in Windows 3. 1, the paper studies the method of Concutrent working for communication program,and presents double message circulating,a technique of control transferring of communication task.

• 本文在分析Windows3.；1多任务并发原理基础上，研究串（并）行通讯程序实现并发的方法，提出了通讯任务转让控制的双消息循环技术。